The present invention relates generally to implantable pumps and more particularly to a device and a method for stimulating penile erection by delivering a vasodilator agent into the penile corpus cavernosus via an implantable delivery line from an implantable pump.
Impotence affects nearly ten million men in the United States alone. There are many causes for impotence in the human male, both pathological and psychological. Such impotence often destroys the male""s psychological well being, and often seriously disrupts or even causes the dissolution of an otherwise fulfilling relationship.
The penis consists of the urethra and three erectile bodies (two corpora cavernosa and a corpus spongiosum. The smooth musculature of these erectile bodies and the smooth muscles of the arteriolar and arterial walls play a key role in the erectile process. In the flaccid state, these smooth muscles are tonically contracted by the sympathetic discharge, allowing only a small amount of arterial flow for nutritional purposes. The flaccid, penis is in a moderate state of contraction, as evidenced by further shrinkage in cold weather. Normally, sexual stimulation triggers the release of neurotransmitters from the cavernous nerve terminals.
This results in relaxation of these smooth muscles and the following events:
dilatation of the arterioles and the arteries by increased blood flow in both the diastolic and systolic phases;
trapping of the incoming blood by the expanding sinusoids (the spaces in between the smooth muscles of the erectile bodies);
compression of the subtunical venous plexus between the tunica albuginea (the fascia that surrounds the erectile bodies) and the peripheral sinusoids, reducing the venous outflow.
stretching of the tunica to its capacity, which encloses the emissary veins between the inner circular and the outer longitudinal layers and further decreases the venous outflow to a minimum;
an increase in intracavernous pressure (maintained at about 100 mm Hg), which raises the penis from the dependent position to the erect state (the full erection phase);
and a further pressure increase (to several hundreds millimeters of mercury)with contraction of the ischiocavernous muscles (rigid erection phase).
Erection thus involves sinusoidal relaxation, arterial dilatation, and venous compression. The importance of smooth muscle relaxation has been demonstrated in animal and human studies.
Several methods are being presently practiced to treat erectile dysfunction: oral agents; topical agents (transcutaneous and transurethral); hormones; vacuum therapy; intracavernous injection of vasodilator agents; and penile prosthesis. The results in all the above methods but the last two are very unsatisfactory. A recently introduced, March 1998, oral agent, VIAGRA, is claimed to have very good results, but with predictable side-effects due to systemic generalized vasodilatation, as this vasodilator agent is not specific for the penis. More clinical studies are still needed to prove its safety.
Intracavernous injection is the modem pharmacological treatment and consists of injecting a vasodilator agent into the corpus cavernosum of the penis, thus avoiding the undesirable systemic effect of the agent. The patient is taught how to perform the injection using a syringe and a needle under aseptic condition.
Erection after injection is achieved secondary to smooth muscle relaxation, resulting in increased blood flow to the erectile bodies. The quality of erection is very close to natural erection; it is warm and hard. A response rate of 80-100% has been achieved, depending on the underlying cause of impotence. However, many patients refuse this modality due to needle phobia and the stigma of carrying a needle and a syringe. Many patients also complain of the lack of spontaneity and interruption of foreplay associated with injecting the medicine.
Penile prosthesis gives good results. The quality of erection is excellent in terms of rigidity but the skin is cold. The implant has a high mechanical failure rate and serious complications and has the disadvantage of irreversibility. In addition, such implants involve gross insult to the normal anatomical structure of the penis.
In U.S. Pat. No. 5,518,499 of May 21, 1996, Agar describes a new device for implantation into the scrotum comprising a housing containing a vasoactive agent and a conduit communicably connected to the housing, and having a length such that when the housing is implanted in the scrotum, a terminal end of the conduit extends to a point in the corpus cavernosum.
Although his patent addresses the need for a device to deliver a vasoactive agent directly into the corpus cavernosum without the need for a syringe and a needle, the device suffers several disadvantages. The housing is filled, according to the description, only once before the incision is closed; the volume of the housing is limited because of its location in the scrotum. Even if the housing is meant to be refillable, there is no special sealing port for refilling; and the site of refilling (the scrotum) carries a higher risk of contamination and infection due to anatomical reasons (proximity to the anal orifice). There is only one terminal catheter into one of the corpus cavernosa. Despite the connection of the two corpus cavernosa, the vasoactive agent is not distributed equally in both corpora. There are are no other patents or articles that address the need for an implantable device that delivers a vasoactive agent internally to the corpus cavernosum.
Implantable pumps have been known for several decades to continuously deliver a selected medication to a certain location in the body in a scheduled or pre-programmed manner. An implantable infusion pump of this general type includes: an internal medication chamber or reservoir for receiving and storing a supply of the selected medication in liquid form; a pump mechanism; a refill port on the pump to permit transcutaneous needle access for purpose of periodically refilling the pump reservoir with a fresh supply of medication; and a catheter connecting the reservoir to the desired location.
Several methods have been described for the pump mechanism and the control of the rate of flow of the medication:
U.S. Pat. No. 3,731,681 describes an implantable infusion pump employing a liquid/vapor to provide a constant pressure for a drug flowing through a capillary tube in order to maintain a constant flow rate.
U.S. Pat. No. 4,772,263 describes an implantable infusion pump comprising a flexible spring diaphragm, which forms an outer back wall portion for housing of the infusion pump. The spring diaphragm applies a substantially constant force over a range of displacement and communicating body pressure to the drug chamber so as to maintain a uniform pressure between the drug chamber and the internal body pressure.
The pump also includes a capillary tubing, which serves as a flow-regulating resistance element or flow restrictor.
Several other pumps are already available in the market for different purposes using different driving forces, regulators, and electronic circuits to control the flow rate without any control by the patient and are inherently unresponsive to changing patient needs.
Few implantable devices are known wherein the patient himself manually actuates the pump in order to selectively deliver a dose from the implanted reservoir to the desired location.
U.S. Pat. No. 4,013,074 describes a device of this type which includes a peristaltic pump that can be manually activated through the skin by means of a suitable mechanical system.
U.S. Pat. No. 4,718,894 of Lazorthes describes a manually actuated implantable device with a manual pump located in the opposite zone of a flexible reservoir.
U.S. Pat. No. 4,813,951 of Cannon describes a pump apparatus, which includes a collapsible reservoir sac for holding fluids to be pumped, and a resilient pump chamber mechanism for withdrawing fluid from the reservoir and for supplying the fluid to a specific location within the body of the patient, but only when the patient manually applies forces to the implanted resilient chamber. The device also includes a windkessel device for extending the flow of the fluid for longer duration at steady flow rates.
None of the implantable pumps, particularly those with continuous flow, is suitable for use in impotency cases.
The present invention overcomes the shortcomings of the previous methods and devices for treating male impotence and provides the following advantages:
It provides a novel method and device for treatment of male impotence without the need for repeated penile needle stick, to achieve a natural physiological erection.
It is another object to overcome the above-described problems associated with the treating impotence.
It is another object of the invention to create a device with a relatively large reservoir that can provide an increased number of doses implanted in the abdominal wall.
It is another object of the invention to provide a deformable reservoir configurated for implantation in the scrotum for dispensing its content to at least one erectile body of the penis, thus allowing easy and reliable use and capable to feed upon each actuation an exact and predetermined dose.
It is another object of the invention to provide a novel catheter tip which allows dispensing the medication from the said deformable reservoir to the erectile bodies without allowing the blood entering and thus blocking the catheter.
Other objects and advantages shall be understood and readily apparent to those skilled in the art upon reading the drawings, specifications and claims appended hereto.
An implantable system for treating male impotence by delivering a vasodilator agent directly to the erectile bodies of the penis comprises an implantable supply pump, deformable reservoir, conducting catheter, and a dispensing catheter. The supply pump is implanted into the abdominal wall. It includes a fluid chamber for holding a vasodilator substance and pressure chamber for exerting a pressure on a plate positioned between the two chambers for delivering the substance into a conducting catheter. The pressure chamber is either spring-driven or driven by a liquid-vapor pressure reservoir. The deformable reservoir is preferably implanted in the scrotum and is manually deformable for forcing the substance therefrom and into a dispensing catheter to the erectile bodies of the penis. The dispensing catheter tip is preferably expandable and is operable to expand when the substance is forced into the catheter. The catheter tip includes a plurality of openings for dispensing the substance therefrom into the erectile bodies.
The object of the present invention is to provide a novel method and device for treatment of male impotence, without the need for repeated penile needle stick, to achieve a natural physiological erection. It is another object to overcome the above-described problems associated with treating impotence. It is another object of the invention to create a device containing a relatively large reservoir that can provide an increased number of doses implanted in the abdominal wall. It is another object of the invention to provide a deformable reservoir configured for implantation in the scrotum for dispensing its content to the erectile bodies of the penis, thus allowing easy and reliable use and capability to feed upon each actuation an exact and predetermined dose.